U.S. patent number 6,880,215 [Application Number 10/136,599] was granted by the patent office on 2005-04-19 for method of manufacturing cushion construction for seating unit.
This patent grant is currently assigned to Steelcase Development Corporation. Invention is credited to Gordon J. Peterson.
United States Patent |
6,880,215 |
Peterson |
April 19, 2005 |
Method of manufacturing cushion construction for seating unit
Abstract
A method of manufacturing a seating unit, such as a chair,
includes manufacturing a cushion made from a non-woven fibrous
material, and attaching the cushion to the seating unit for
comfortable support. The cushion is made by cutting a blank from
non-woven fibrous sheet material, steam-forming the blank into a
pre-formed cushion shaped to support a user, and attaching a
stiffener panel to the pre-formed cushion to provide a stiffened
cushion assembly. The cushion assembly is aesthetically covered and
assembled to seating unit. Advantageously, trimmings from the
fibrous material can be recycled.
Inventors: |
Peterson; Gordon J. (Rockford,
MI) |
Assignee: |
Steelcase Development
Corporation (Caledonia, MI)
|
Family
ID: |
43379009 |
Appl.
No.: |
10/136,599 |
Filed: |
May 1, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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294665 |
Apr 19, 1999 |
6425637 |
|
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Current U.S.
Class: |
29/91.1; 29/448;
297/452.3; 297/452.31 |
Current CPC
Class: |
A47C
7/24 (20130101); A47C 7/46 (20130101); A47C
31/023 (20130101); Y10T 29/49867 (20150115); Y10T
29/481 (20150115) |
Current International
Class: |
A47C
31/02 (20060101); A47C 31/00 (20060101); D04H
1/00 (20060101); B68G 007/00 () |
Field of
Search: |
;29/91.1,448
;297/180.1,180.11,180.13,180.14,452.31,452.32,452.33,452.42,452.43,452.3,452.46,452.47,452.48,452.55,452.56 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Omgba; Essama
Attorney, Agent or Firm: Price, Heneveld, Cooper, DeWitt
& Litton, LLP
Parent Case Text
CROSS REFERENCES TO RELATED APPLICATION
This application is a divisional of commonly assigned, co-invented
application Ser. No. 09/294,665, now issued U.S. Pat. No.
6,425,637, entitled CUSHION CONSTRUCTION FOR FURNITURE.
Claims
The invention claimed is:
1. A method comprising the steps of: cutting a blank from a sheet
of non-woven fibrous material; forming the blank into a pre-formed
cushion shaped as a back for a seating unit; attaching a cushion
stiffener to the cushion to provide additional structure to the
cushion; providing a back support panel having a stiff thoracic
section and a flexible lumbar section, and the cushion stiffener
having a vertical length not substantially greater than the
thoracic section so that the lumbar section maintains a
flexibility; and attaching the cushion stiffener to the support
panel to define a back support assembly by engaging first
mechanical connectors on the cushion stiffener with second
mechanical connectors on the support panel, with the cushion
stiffener extending across a substantial portion of the thoracic
section, such that the cushion stiffener does not substantially
increase the stiffness of the back support assembly in the region
of the flexible lumbar section of the support panel.
2. The method defined in claim 1, including covering the cushion
with a cover assembly that forms a sock around the cushion.
3. The method defined in claim 2, including covering the cushion
with fabric material and: providing a high-stretch material along a
lower portion of the cushion; stretching the high-stretch material
across the lumbar section of the support panel; attaching the
high-stretch material to the support panel.
4. The method defined in claim 2, wherein the support panel is
shaped to support a seated user's back, and including steps of
providing a chair with a back frame and attaching the support panel
to the back frame.
5. The method defined in claim 1, wherein the fibrous material
includes PET material.
6. The method defined in claim 1, wherein: the cushion stiffener
includes an enlarged, generally rectangular opening
therethrough.
7. A method comprising the steps of: cutting a blank from a sheet
of non-woven fibrous material; forming the blank into a pre-formed
cushion shaped as a back for a seating unit; covering the cushion
with a cover assembly that forms a sock around the cushion;
providing a back support panel having a stiff thoracic upper
section, and a lower lumbar section having a plurality of elongated
horizontal slots therein providing flexibility in the lumbar
section, the support panel having a pivot connector at a lower
portion to pivotably connect the back support panel to a seating
unit; and attaching a subassembly of the cushion and the cover
assembly to the support panel, with both the support panel and the
subassembly permitting air flow therethrough.
8. The method defined in claim 7, wherein the cover assembly
includes a fabric panel of stretch material, and including
stretching the fabric panel when attaching the cover assembly over
and onto the cushion.
9. The method defined in claim 8, wherein the support panel is
shaped to support a seated user's back, and including steps of
providing a chair with a back frame and attaching the support panel
to the back frame.
10. A method of manufacturing a seating unit comprising the steps
of: providing a seat support that is air permeable and adapted to
be supported by a base; providing a back upright adapted to be
operably supported by one of the base and the seat support for
movement between an upright position and an angled position;
attaching a back support to the back upright, the back support
being air permeable and defining a stiff upper thoracic section and
a flexible lower lumbar section; assembling a cushion assembly
including providing a non-woven fibrous mat of cushioning material
that is air-permeable, and attaching a stiffener panel to the
cushion material; and positioning the cushion assembly on the back
support and wherein the stiffener panel does not substantially
stiffen the back assembly in the region of the lower lumbar
section.
11. The method defined in claim 10, including pre-forming the
cushion material to include a feature line formed into the cushion
material.
12. The method defined in claim 10, wherein the step of pre-forming
the cushion material includes forming depressions in the cushion
material, but with the cushion material maintaining a predetermined
uniform density and an absence of flash lines or parting lines.
13. The method defined in claim 10, wherein: the stiffener panel
includes an enlarged, generally rectangular opening
therethrough.
14. A method of manufacturing a seating unit comprising the steps
of: providing a non-woven fibrous mat of cushioning material that
is air-permeable; trimming the fibrous mater to a predetermined
shape; pre-forming the fibrous mat by using a heating process;
attaching a stiffener panel to the cushion material to form a
cushion assembly; positioning the cushion assembly on a back
support having a flexible lower lumbar portion on a seating unit
for comfortably supporting a seated user; and attaching the cushion
assembly to the support by releasably engaging hooks on the
stiffener panel with apertures in the support, wherein the
stiffener comprises a panel that extends over an upper portion of
the back support, and defines a generally horizontal lower edge
above the lumbar portion of the back support.
15. The method defined in claim 14, wherein the step of pre-forming
include heating the fibrous mat in a manner not causing a parting
line on the pre-formed fibrous mat.
16. A method comprising the steps of: cutting a blank from a sheet
of non-woven fibrous material; forming the blank into a pre-formed
cushion shaped as a back or seat on a seating unit; attaching a
cushion stiffener to the cushion to provide additional structure to
the cushion; providing a support panel and attaching the cushion
stiffener to the support panel by engaging first mechanical
connectors on the cushion stiffener with second mechanical
connectors on the support panel; covering the cushion with a cover
assembly that forms a sock around the cushion, the cover assembly
including stretchable material extending along a lower portion of
the cover assembly, and a stiffening flange attached to a lower
edge of the stretchable material, and wherein: the cover assembly
is attached to the support panel by connecting the stiffening
flange to the support panel.
17. The method defined in claim 16, wherein the first back panel is
stretchable material the support panel includes a horizontally
elongated recess that opens generally downwardly, and: connecting
the stiffening flange to the support panel includes inserting the
stiffening flange in the elongated recess such that tension in the
stretchable material retains the stiffening flange in the recess.
Description
BACKGROUND OF THE INVENTION
The present invention relates to methods of manufacturing cushion
constructions for seating, where the cushion has improved
cushioning properties.
Chairs having upholstery covered cushions on their seat and backs
are known. The cushions provide a cushioning effect that conforms
at least somewhat to a seated user's body to provide increased
comfort. A common cushion in chairs is a polyurethane open-celled
foam cushion that is pre-formed to an initial shape. For example,
U.S. Pat. No. 4,718,153, to Armitage et al., issued Jan. 12, 1998,
entitled Cushion Manufacturing Process, discloses one such cushion
manufacturing process utilizing a polyurethane foam. A problem is
that the polyurethane will degrade over time, leading to breakdown
of the polyurethane foam that generates dust and a degradation of
cushioning properties. The dust and breakdown potentially adds to
environment dust in the building where the chair is located. Also,
the breakdown and loss of material results in changes to the
cushioning support provided by the cushion. Polyurethane foam
cushions also suffer from other disadvantages. Polyurethane foam is
not recyclable, leading to increased landfill costs when scrap is
generated. Further, the polyurethane foam typically has a
pinched-off edge or weld line of higher density material running
around its perimeter. The higher density material can cause quality
problems, both in terms of poor appearance due to its roughness,
stiffness, and protruding nature, and also in terms of an
unattractive bumpy feel when a person sits on or feels the fabric
covering the higher density material. Still another problem is
caused when a seated user sweats against a polyurethane foam
cushion, because the polyurethane foam cushions are sometimes not
able to wick away the sweat (or at least not fast enough),
depending on the foam and the volume of sweat.
Accordingly, an improved cushion construction for furniture is
desired that solves the aforementioned problems and has the
aforementioned advantages.
SUMMARY OF THE INVENTION
One aspect of the present invention includes a method comprising
steps of cutting a blank from a sheet of non-woven fibrous material
and forming the blank into a pre-formed cushion shaped as a back or
seat on a seating unit.
In another aspect of the present invention, a method of
manufacturing a seating unit includes steps of providing a seat
support adapted to be supported by a base, providing a back upright
adapted to be operably supported by one of the base and the seat
support for movement between an upright position and an angled
position, and attaching a back support to the back upright. The
method further includes assembling a cushion assembly including
providing a non-woven fibrous mat of cushioning material that is
air-permeable, and attaching a stiffener panel to the cushion
material, and still further includes positioning the cushion
assembly on at least one of the back support and the seat
support.
In another aspect of the present invention, a method of
manufacturing a seating unit includes steps of providing a
non-woven fibrous mat of cushioning material that is air-permeable,
trimming the fibrous mat to a predetermined shape, and pre-forming
the fibrous mat by using a heating process. The method further
includes attaching a stiffener panel to the cushion material, and
positioning the cushion assembly on a seating unit for comfortably
supporting a seated user.
These and other features, objects, and advantages of the present
invention will become apparent to a person of ordinary skill upon
reading the following description and claims together with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 are front and rear perspective views of a chair
embodying the present invention;
FIG. 3 is an exploded front perspective view of the back
construction shown in FIG. 1;
FIG. 4 is a vertical cross-sectional view taken through a center of
the back construction shown in FIG. 1;
FIGS. 5 and 6 are enlarged views of the circled areas V and VI in
FIG. 4;
FIG. 7 is an exploded perspective view of the stiffened cushion
subassembly shown in FIG. 3;
FIG. 8 is a perspective view of the cover assembly shown in FIG.
3;
FIG. 9 is a rear view of the cushion assembly shown in FIG. 3,
including the stiffened cushion subassembly and the cover
assembly;
FIG. 10 is a front perspective view, partially broken away, showing
the back construction of FIG. 3;
FIG. 11 is a rear view of a modified cushion assembly similar to
that shown in FIG. 9, but with edge stiffener legs extending
downwardly along side edges of the cushion pad;
FIG. 12 is a side view of the modified cushion assembly shown in
FIG. 11;
FIG. 13 is a flow diagram showing a method of assembly; and
FIG. 14 is a force versus deflection curve comparing the novel
cushion of non-woven PET fibers to a conventional polyurethane foam
cushion.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
A chair 20 (FIGS. 1 and 2) embodying the present invention includes
a base 21, a back upright or arch-shaped back frame 22, a seat 23,
and a back construction 24. The base 21 includes a control housing
25, with fixed side support structures 26 extending laterally and
upwardly from the control housing 25. The back upright 22 is
movable between an upright position and a reclined position. The
back construction 24 (FIG. 3) includes a back support shell 27
(also referred to as a "back support") attached to the back upright
22 (FIG. 4), and further includes a cushion assembly 28 (FIG. 3)
attached to the back support shell 27 with quick-attach hooking top
connection 29 and a "zip-lock" type bottom connection 30. The
cushion assembly 28 includes a cover assembly 31 (FIG. 8) having an
upholstery front panel 32 and a rear panel 33 forming a sock that
can be inverted and "pulled" upwardly onto a cushion 35 and cushion
stiffener 34 as the cover assembly 31 is inverted. The rear panel
33 includes a first sheet/fabric section 36 having a
one-directional stretch in a vertical direction, and further
includes a lower second fabric section 37 having a high-stretch
property. The second section 37 hangs downwardly from the front
panel 32 and has a strip of stiff material 38 sewn along its lower
edge to form the stiffened edge flange 39 noted below, which
stiffened edge flange 39 forms part of the bottom connection 30.
The stretchable second section 37, in combination with the other
structure of top and bottom connections 29 and 30, allow for quick
assembly, yet provide for a tensioned cover assembly 31 on the back
construction 24 that tends to remain flat and unwrinkled, even with
considerable flexure of the back construction 24 in the lumbar
region of the back construction 24.
The present description of chair 20 is believed to be sufficient
for an understanding of the present combination. Nonetheless, it is
noted that a more detailed description of the chair 20 can be found
in U.S. Pat. No. 5,871,258, issued Feb. 16, 1999, entitled Chair
with Novel Seat Construction, and also in U.S. Pat. No. 5,975,634,
issued Nov. 2, 1999, entitled Chair Including Novel Back
Construction, the entire contents of both of which are incorporated
herein in their entirety by reference. It is to be understood that
a scope of the present invention includes using the present
attachment and construction methods in combination with different
office chairs, but also in many other chairs and seating units
where upholstery covering is desired, such as in couches, lounge
seating, mass transit seating, automotive or bus seating, and
stadium seating, or also in other upholstery-covered furniture,
such as padded desking furniture and the like, and also in
non-furniture situations where upholstery or sheeting must be
attached to a flexible or bendable component in a wrinkle-free
manner.
The back support shell 27 (FIG. 4) comprises a sheet of
polypropylene material or similar engineering-type stiff structural
material, and includes relatively stiff thoracic and pelvic
sections 41 and 42 connected by a flexible lumbar section 43. The
back support shell 27 is relatively stiff in a plane defined by the
sheet, but is flexible in the lumbar section 43 in a direction
perpendicular to the sheet. The thoracic and pelvic sections 41 and
42 are attached to the back frame 22 at top and bottom pivot
locations 44 and 45, and the lumbar section 43 protrudes forwardly
from the thoracic and pelvic sections 41 and 42. A belt bracket 46
extends parallel a lower edge of the pelvic section 42, and
includes forwardly extending side flanges 47 each having a hole
defining the bottom pivot location 45. The belt bracket 46 is
encapsulated in an enlarged section 48 that extends along the lower
edge of the pelvic section 42, and forms a horizontal recess 49
defined between a longer rear lip 50 and a shorter front lip 51.
Slots 52 extend horizontally across a center area of the lumbar
section 44 to form horizontal bands 54, but terminate short of the
edges of the lumbar section 44 to define vertical side edge bands
55 (FIG. 3). The horizontal and vertical bands 54 and 55 are
semi-flexible and designed to be sufficient in size and strength to
provide the support desired. Due to the locations of top and bottom
pivot locations 44 and 45 and also due to the shape and
characteristics of the sections 41-43 and belt bracket 46, the back
support shell 27 flexes significantly in the lumbar area, but
rotates along a predetermined path a substantial amount around the
bottom pivot location 45 and to a lesser extent around the top
pivot location 44. This results is significant wrinkling of the
upholstery material, unless the back construction 24 is constructed
to compensate and make up for this high flexure, and the high
compressing and stretching of the surfaces (i.e., the upholstery)
in the lumbar section 43.
The thoracic section 41 (FIG. 6) includes a ridge 57 along its
upper edge and a series of hooks 58 spaced below the ridge 57 that
project forwardly and then upwardly. A pair of apertures 59 is
spaced below the hooks 58. The apertures 59 are positioned to
receive screws 60 (FIG. 4) that extend rearwardly through the
apertures 59 into threaded engagement with bosses 61 near a top of
the arch-shaped back frame 22. The apertures 59 are recessed to
create a rearwardly deformed pocket to receive a head of the screws
60 as desired. A pair of alignment stops 62' is located in the
recesses on a front of the back support shell 27 adjacent apertures
59 to assist in assembly, as described below.
A pair of saw-tooth ridges 63 (FIG. 3) extends along a front face
of the vertical bands 55 at a location near to but spaced inwardly
from outer edges of the bands 55. A lumbar adjustment device 65 is
positioned between the cushion assembly 28 and the back support
shell 27. The lumbar adjustment device 65 includes a carrier 66, a
lumbar support member 67 with vertical leaf-spring-like fingers 68
supported on the carrier 66, and a pair of side handles 69. The
side handles 69 telescopingly engage mating structures 70 on ends
of the carrier 66, and further include a channel for slidably
engaging the saw-tooth ridges 63. A detent on the handles 69
engages the saw-tooth ridges 63 to hold the lumbar adjustment
device in a selected vertical position.
The cushion assembly 28 includes a back cushion 35 (FIG. 3) formed
of non-woven PET fibers, as described below. The back cushion 35
provides an excellent initial support and feel to a seated user
when he/she initially leans against the cushion assembly 28, even
without use of a topper sheet commonly used in the seating
industry. The cushion stiffener 34 comprises a stiff polypropylene
panel. The cushion 35 includes a rear surface shaped to mateably
receive the cushion stiffener 34. An upper edge 74 (FIG. 7) on a
rear surface of the cushion 35 is wrapped over the upper edge 74
and onto a rear surface of the cushion stiffener 34. The cushion
stiffener 34 is adhered to the cushion 35 if needed to maintain the
stability of the assembly desired. The cushion stiffener 34
includes a series of spaced-apart apertures 75 that correspond to
the hooks 58 (FIG. 3). A horizontal down flange 76 (FIG. 7) extends
along a lower edge of the cushion stiffener 34, which flange 76 is
deformed inwardly toward the cushion 35 at least a thickness of the
material of rear panel 33, so that the rear panel 33 does not
protrude outwardly when attached to the flange 76, as described
below. The cushion 35 has a recess 76' that mateably engages the
flange 76.
As noted above, the cover assembly 31 (FIG. 8) includes a front
panel 32 and a rear panel 33. The front panel 32 includes sections
of upholstery material sewn together to form the front and sides of
a covering for the cushion 35. The rear panel 33 includes the first
fabric section 36, which comprises a material that stretches
horizontally only about five percent (5%), but that stretches
vertically about forty percent (40%). The one-directional stretch
material is available in commerce, such as from Milliken Company,
Spartanburg, S.C. This first fabric section 36 is sized to extend
from the mid-level horizontal flange 76 on the cushion stiffener 34
downwardly to a bottom of the cushion 35. The second section 37 is
a high-stretch material having a stretchability of about one
hundred percent (100%). This second section 37 is about two inches
high and extends across a bottom of the rear panel 33 of the cover
assembly 31. A strip of stiffener material 78, such as
polypropylene, is about 1/4-inch wide in a vertical direction and
is placed along a lower edge of the second section 37. The lower
edge is folded over the strip 78 and sewn to the lower edge. This
forms a stiffened edge flange 79 horizontally across the second
section 37 that is optimally suited to be pressed or "zipped" into
and frictionally retained in the horizontal recess 49 with a
zip-lock like motion (see FIG. 5). Notably, the stiffened edge
flange 79 is rectangular in shape and is rolled forwardly 180
degrees before it is inserted into the recess 49 (FIG. 5). This
results in a surprisingly positive and secure bottom connection
arrangement and one that can be quickly made by an assembler. The
top rear edge of the front panel 32 (FIG. 6) is folded and sewn to
form a tunnel 79', and a drawstring 80 is located in the tunnel.
The front and rear panels 32 and 33 are sewn together to form an
upwardly open sock. The panels 32 and 33 are initially sewn in an
inverted position, and the cushion 35 is inserted into the sock as
the sock in inverted. This also hides the seam lines where the
panel 32 and first and second fabric sections 36 and 37 are sewn
together.
FIG. 13 discloses a method including forming a sock-like cover
assembly 31 in a step 90 from the panels 32 and 33 and second
fabric section 37. Step 90 further includes sewing a strip 78 to a
bottom of second fabric section 37 and attaching a drawstring 80 in
a tunnel 79'. A second step 91 includes attaching cushion stiffener
34 to the cushion 35. The cover assembly 31 is positioned adjacent
the cushion 35 and inverted onto an end of the cushion 35 opposite
the cushion stiffener 34 in a step 92. This results in the
high-stretch second fabric section 37 being positioned at a lower
edge of the cover assembly 31 remote from the cushion stiffener 34.
The cover assembly 31 is then adjusted on the cushion 35 and
cushion stiffener 34 to eliminate wrinkles and to properly position
the seam lines. This may include tensioning the drawstring 80, as
shown in step 93. Specifically, in the illustrated embodiment, the
drawstring 80 is tensioned to draw a top of the cover assembly 31
downwardly onto the cushion stiffener 34. This also tensions the
front panel 32. The tensioned drawstring 80 helps hold the cover
assembly 31 in position during the steps of inserting staples 82
and 83, and during a step of setting any adhesive in the assembly.
The front panel 32 is then staple-attached along its upper edge to
the cushion stiffener 34 by staples 82 (FIG. 9) that extend through
the wrapped-over top edge of the front panel 32 into the cushion
stiffener 34. The upper edge 33' of the rear panel 33 is overlapped
onto the down flange 76 and is stapled with staples 83 that extend
through the upper edge into the down flange 76. Where desired,
heat-activated adhesive is applied to a front surface of the
cushion 35, and the adhesive is activated by steam or heat to
adhere the front panel 32 to the cushion 35. This assembly results
in cushion assembly 28.
The back support shell 27 of the back construction 24 (FIG. 13) is
attached in a step 94 to the back frame 22 by screws at the top
connection 44 and by pivot studs at the bottom connection 45. A
lumbar force adjusting device 95 (FIG. 1) is attached to the back
frame 22 to bias the flange 47 of belt bracket 46, such that the
lumbar section 43 of the back support shell 27 naturally is biased
to a forwardly concave shape.
The cushion assembly 28 is assembled onto the back support shell 27
in a step 96 (FIG. 13) to form the back construction 24 by abutting
stops 62' on the cushion stiffener 34 against the stops 62' on the
back support shell 27, and by extending the hooks 58 on the
thoracic section 41 of the back support shell 27 into the apertures
75 of the cushion stiffener 34. Then, the back cushion 35 including
the cushion stiffener 34 is moved downwardly to frictionally engage
the hooks 58. Thereafter, the stiffened edge flange 39 at the
bottom of the rear panel 33 is stretched, rolled 180 degrees, and
tucked upwardly into the downwardly facing horizontal recess 49 on
the back support shell 27 (in a step 97). The stiffened edge flange
39 is tucked into position from one side to another with a
"zip-lock" type motion. After it is fully inserted, the side edges
of the high-stretch second section 37 are pulled back, and a staple
is extended through the stiffened edge flange 39 into each end of
the rear lip 50 in a step 98. The high-stretch second section 37 is
then pulled laterally out to a wrinkle-free condition where it
hides these end-located staples. Notably, the high-stretch second
section 37 is a dark or black color and is located behind the seat
23 below the back construction 24 in the shadow of the back
construction 24, such that the bottom connection 30 including the
enlarged section 48 of the back support shell 27 is not easily
visible to a person standing in or around the chair 20.
In the embodiment of FIGS. 11 and 12, a modified cushion stiffener
34A is provided that includes an upper portion like the stiffener
34, but further includes perimeter bands 34B that extend down side
edges and along a bottom of the cushion 35 to stiffen the edges
completely around the cushion 35. Cushion stiffener 34A is
desirable where the fabric panels 32 or 33 are so strong as to
overpower the cushion edges causing wrinkling.
As noted above, the cushion 35 is made from a recycled non-woven
PET fibrous mat supplied by Sackner Co., Grand Rapids, Mich. The
PET mat is molded to form a novel cushion that is substituted for
the polyurethane cushion and the topper cushion often used in prior
art. Non-woven polyester or PET is a polyester with a phenylene
group in a chain. The stiffness of this chain is what allows the
thermoplastic to perform surprisingly and unexpectedly well as a
cushioning fiber, as discussed below.
When PET completely burns, it turns into carbon dioxide and water
and does not emit any poisonous gases. Food products can be
packaged in this material without any worry, and containers can be
burned without the need for extraordinary emission control
measures. This is not true for polyurethane, which will emit
dangerous byproducts when burned. Use of PET material is also
environmentally friendly. A major source of the PET material for
cushion 35 comes from re-ground pop bottles. Recycling of PET pop
bottles into headliner cores, insulation, and door panels has
apparently been previously done. However, its use as a complete
cushion for a chair seat or chair back has not been done to my, the
inventor's, knowledge.
A major advantage of the PET cushion material are that it is 15 to
20 percent lighter than polyurethane foam, yet it provides a high
value and high value per unit cost. Further, the PET cushion
material provides improved comfort to a seated user including a
very uniform force versus deflection curve (see FIG. 14) with a
surprisingly constant slope over a major portion of its
compression. The more conventional polyurethane foam has a much
less constant rate of compression. Often a topper cushion (e.g.,
about a 1/4-inch thick cushion) is placed on a main cushion (e.g.,
about a 1 inch thick cushion) to "smooth out" the initial
compression of the main cushion. However, this adds considerable
expense. The non-woven fibrous cushion 35 does not need any such
topper cushion. Further, the PET cushion material provides more
breathability including the ability to wick away a seated user's
sweat, provides excellent fatigue resistance and long life with
little or no generation of dust after extended time in service,
provides a capability of easy and low-cost recycling, and has no
carcinogens or VOC's in its manufacture. Further, my initial
research indicates that replacing molded foam with an equivalent
piece of PET cushion results in a break-even or a decrease in
costs.
Thermal comfort studies done by or for Steelcase, the assignee of
the present invention, indicate a 50 percent higher/greater
moisture permeability index in the supplied PET cushion than molded
urethane foam cushions. This is believed to be due to the more open
internal (fibrous) structure of the PET material. Higher index
numbers equate to more desirable comfort. Also, the evaporative
resistance of the PET cushion is less than half that of the molded
foam cushion. The lower evaporative resistance correlates to
improved comfort also in that the moisture given off by the body is
absorbed and dispersed through the PET cushion much faster than
through the molded urethane cushion.
Testing of the PET and molded urethane foam, using tests known to
persons skilled in making chairs, indicates a lower initial load
deflection characteristic of the PET cushions over the more
traditional urethane foams, but a higher support factor, better
ball rebound, better tensile strength and elongation, and a more
linear cushioning rate. Tests suggest the feel to be more
"residential" verses "industrial" (see FIG. 14).
Advantageously, the non-woven PET cushion can be formed into a
three-dimensional shape to conform properly to a particular chair
geometry. Leaving the material in a flat shape and attaching it to
the chair can result in a "kinking" of the PET material in some
highly contoured chair designs, which may telegraph a crease or
wrinkle into the face fabric of these chairs.
My proposed system works as follows. For the seat 23 of chair 20,
batting of material is optimally produced to a known raw mat
density and thickness, such as about 2.3 to 2.6 lb./ft.sup.3, with
a thickness of about 2 inches (unformed) or about 2.3 to 3.5
lb./ft.sup.3 density (or more preferably between about 3.1 to 3.5
lb./ft.sup.3) with a thickness of about 11/2 inches (formed). A
similar density of about 2.3 to 2.6 lb./ft.sup.3 is used for back
cushion 35, but the thickness is different. For example, in cushion
35 the thickness is about 1 inch (unformed) or about 2.3 to 5.2
lb./ft.sup.3 density (or more preferably between about 4.6 to 5.2
lb./ft.sup.3) with a thickness of about 1/2 inch (formed). The
material is cut to a predetermined size with a die cut, laser cut,
or any other efficient means of trim. This pre-form is then loaded
into a three-dimensional aluminum tool cavity of the desired shape.
The cavity and lid are both pre-drilled to allow steam to pass
through the tool halves. The material is then introduced to about a
30 second (plus or minus 5 to 10 seconds) steam heating cycle of
about 250 degrees Fahrenheit that breaks the temporary thermal
adhesive bond, and a 10 second (plus or minus 5 seconds) cooling
cycle of ambient air that allows the material to rebond in the
desired three-dimensional shape. The memory of the material is thus
changed to the new shape and the part is removed from the tool.
Since no edge trimming is required, edges can be produced round,
and since the edges are not trimmed, edges do not have a hard edge
or look non-uniform. Less handling and sensitive trimming also
result in reduced costs of manufacture. Also, there is no scrap in
terms of flashing or trimmings from the forming process, and any
scrap, if generated, can be recycled.
The compressibility and shape of the cushion is also more uniform,
since a uniformly produced batting of material, cut to a controlled
size, was loaded into the tool and no materials were discarded in
the forming process. Feature lines, depressions, and the like can
be molded or pressed into the cushion material. Characteristically,
no flash lines or parting lines are formed, such that the marginal
material around a perimeter of the part feels the same as (and has
the same density and compressibility as) the main part of the
cushion.
In the foregoing description, it will be readily appreciated by
persons skilled in the art that modifications may be made to the
invention without departing from the concepts disclosed herein.
Such modifications are to be considered as included in the
following claims, unless these claims by their language expressly
state otherwise.
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